Fuel injection device

ABSTRACT

In a fuel injection device having a sensor for detecting a state in the combustion chamber in a free end thereof, the noises that may be generated in the sensor signal transmitting member for transmitting the sensor signal are minimized. The fuel injection device comprises: a valve body ( 33 ) having a free end exposed to the combustion chamber ( 7 ) defined in the engine main body ( 3 ) and a base end located outside of the engine main body; a sensor ( 38 ) supported at a free end of the valve body to detect a state of the combustion chamber; an actuator ( 37 ) received in the valve body; a sensor signal transmitting member ( 91, 128 ) extending from the sensor to the base end of the valve body; a drive signal transmitting member ( 83, 84 ) extending from the actuator; and a first shield member ( 133 ) interposed between the sensor signal transmitting member and the drive signal transmitting member, the first shield member having an electro-conductive property and being grounded.

TECHNICAL FIELD

The present invention relates to a fuel injection device for internalcombustion engines, and in particular to a fuel injection device havinga sensor for detecting a state of the combustion chamber mounted on thefree end thereof.

BACKGROUND OF THE INVENTION

In a direct injection engine, a fuel injection device is mounted on thecylinder head such that the free end of the valve body defining theouter shell of the fuel injection device is exposed in the combustionchamber. Fuel injection orifices are formed at the free end of the valvebody, and the fuel is injected into the combustion chamber from theinjection orifices according to the movement of a valve member providedin the valve body. It has been proposed to support a pressure detectiondevice at the free end of the valve body in such a fuel injection deviceto detect the pressure in the cylinder. See Patent Document 1, forinstance. According to the fuel injection device disclosed in PatentDocument 1, the pressure detection device is provided with an annularconfiguration so as to receive the free end of the valve body therein,and welded to the valve body so as to be exposed to the combustionchamber.

In such a fuel injection device, because the pressure detection deviceis supported by the valve body, there is no need to change theconfigurations of the combustion chamber or the cylinder head forinstalling the pressure detection device. Because there is no contactbetween the pressure detection device and the cylinder head, vibrationsthat could be transmitted to the pressure detection device from sourcessuch as other cylinders, the valve actuating mechanism and the headcover via the cylinder head can be minimized. Also, the pressuredetection device is protected from thermal damages owing to the coolingeffect of the fuel that passes through the valve body.

PRIOR ART DOCUMENT(S) Patent Documents(s)

Patent Document 1: WO2012/115036

SUMMARY OF THE INVENTION Task to be Accomplished by the Invention

In such a fuel injection device having a pressure detection device atthe free end of the valve body, it is important to properly wire (layout) the detection signal transmitting wire (detection signaltransmitting member) for transmitting the signal from the pressuredetection device. The detection signal transmitting wire is required tobe drawn out from the base end of the valve body which is located awayfrom the cylinder head to be connected to an external circuit.Additionally, the fuel injection device requires a drive signaltransmitting wire (drive signal transmitting member) for transmittingthe drive signal (voltage) to an actuator such as a solenoid and a piezodevice to drive the valve member. If these two transmitting wires areplaced too close to each other, the electromagnetic field produced fromthe drive signal transmitting wire may create noises in the detectionsignal transmitted by the detection signal transmitting wire.

In view of such a problem of the prior art, a primary object of thepresent invention is to reduce the noises in the detection signal in afuel injection device having a sensor for detecting a state of thecombustion chamber mounted on the free end thereof.

Means to Accomplish the Task

To achieve such an object, the present invention provides a fuelinjection device, comprising: a valve body (33) having a free endexposed to a combustion chamber (7) defined in an engine main body (3)and a base end located outside of the engine main body; a sensor (38)supported at the free end of the valve body to detect a state of thecombustion chamber; an actuator (37) received in the valve body; asensor signal transmitting member (91, 128) extending from the sensor tothe base end of the valve body; a drive signal transmitting member (83,84) extending from the actuator; and a first shield member (133)interposed between the sensor signal transmitting member and the drivesignal transmitting member, the first shield member having anelectro-conductive property and being grounded.

According to this structure, because the first shield member serves asan electromagnetic shield that blocks the electromagnetic fieldgenerated by the drive signal transmitted by the drive signaltransmitting member, the sensor signal transmitted by the sensor signaltransmitting member is prevented from being contaminated by noises.

In such an invention, it is preferred that the valve body is providedwith an electro-conductive property and grounded via the engine mainbody, and the first shield member is supported by and electricallyconnected to the valve body.

According to this structure, the grounding structure for the firstshield member can be simplified, and the overall structure of the fuelinjection device may be simplified.

In such an invention, the fuel injection device may further comprise afirst resin portion (39) molded to the base end of the valve body todefine a connector portion (120), a first connecting terminal (124)placed in the connector portion and connected to the sensor signaltransmitting member, and a second connecting terminal (125, 126) placedin the connector portion and connected to the drive signal transmittingmember, the first shield member being at least partly buried in thefirst resin portion.

According to this arrangement, by combining the connectors for thesensor and the actuator into a single connector portion, the structureof the fuel injection device can be simplified, and the connectingprocess can be simplified. Also, the first shield member may besupported by the first resin portion that forms the connector portion,and the sensor signal transmitting member may be shielded from the drivesignal transmitting member within the first resin portion.

In such an invention, the first shield member may include a part (138)interposed between the first and second connecting terminals.

According to this arrangement, the first connecting terminal may beshielded from the second connecting terminal.

In such an invention, the fuel injection device may further comprise asecond resin portion (40) molded to the valve body and the first resinportion and covering the sensor signal transmitting member, and a secondshield member (150) having an electro-conductive property and coveringthe second resin portion, the second shield member being electricallyconnected to a part of the first shield member extending from the firstresin portion.

According to this arrangement, the second shield member blocks theelectromagnetic field created by external sources, and prevents anynoises to be produced in the sensor signal transmitted by the sensorsignal transmitting member. For instance, the second shield memberblocks the electromagnetic field produced by the drive signalstransmitted by the drive signal transmitting members of any adjoiningfuel injection devices.

In such an invention, it is preferred that the second connectingterminal comprises a pair of second connecting terminals which areplaced on either side of a diametric line extending perpendicular to anaxial line of the valve body, and the first connecting terminal ispositioned on a side of one of the second connecting terminals facingaway from the other second connecting terminal.

Thereby, the fuel injection device can be readily adapted to both themodels that are provided with the sensor signal transmitting member inaddition to the drive signal transmitting member and the models that arenot.

In such an invention, a distance between the first connecting terminaland the adjoining second connecting terminal may be greater than adistance between the two second connecting terminals.

Thereby, the first connecting terminal is adequately spaced from both ofthe second connecting terminals so that the influences of theelectromagnetic field created by the second connecting terminals on thefirst connecting terminal can be minimized.

Effect of the Invention

Owing to such a structure, in a fuel injection device provided with asensor for detecting a condition in the combustion chamber in a frontend part thereof, the noises that may be induced in the sensor signaltransmitting member for transmitting the sensor signal may be minimized.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a sectional view of an internal combustion engine including afuel injection device given as a first embodiment of the presentinvention;

FIG. 2 is a perspective view of the fuel injection device (with theshield cover removed);

FIG. 3 is a side view of the fuel injection device;

FIG. 4 is a perspective view of the fuel injection device as seen in thedirection indicated by arrow IV in FIG. 3;

FIG. 5 is a sectional view of the fuel injection device as mounted onthe internal combustion engine;

FIG. 6 is an enlarged sectional view of a free end of the fuel injectiondevice;

FIG. 7 is a perspective view of the fuel injection device (with theshield cover, the second resin portion and the stay member removed);

FIG. 8 is a perspective view of the wiring structure for the first andsecond sensor wire;

FIG. 9 is the wiring structure for the first sensor wire, (A) showingthe first sensor wire positioned on the exterior of the large diameterportion, and (B) showing the first sensor wire positioned in the firstreceiving groove of the small diameter portion;

FIG. 10 is a perspective view of the fuel injection device (with theshield cover removed, and with the first and second resin portionsshowing through);

FIG. 11 is a perspective view similar to FIG. 4 showing a fuel injectionvalve given as a modification of the first embodiment;

FIG. 12 is a block diagram showing the structure of the fuel injectionvalve;

FIG. 13 is a side view of a fuel injection valve shown partly insection;

FIG. 14 is an external perspective view of the fuel injection valvegiven as a second embodiment;

FIG. 15( a) is a fragmentary sectional view of a free end part of thenozzle member, and FIG. 15( b) is a sectional view taken along line A-A;

FIG. 16 is an external perspective view of the fuel injection valvebefore the secondary mold member is molded thereto;

FIG. 17 is a partly broken away external perspective view of the fuelinjection valve after the secondary mold member has been molded thereto;

FIG. 18 is a side view of the fuel injection valve before the secondarymold member is molded thereto shown partly in section;

FIG. 19( a) is a view illustrating the process of positioning the signalwire relative to the projecting part, and FIG. 19( b) is a viewillustrating the process of connecting the signal wire relative to theprojecting part;

FIG. 20( a) is a view illustrating the process of applying a bondingagent to the connected part between the signal wire and the projectingpart, and FIG. 20( b) is a view illustrating the process of molding thesecondary mold member;

FIG. 21 is a view illustrating how the moisture advances in theinterface between the connector mold member and the secondary moldmember;

FIG. 22 is a side view of the fuel injection valve given as a thirdembodiment shown partly in section; and

FIG. 23 is an external perspective view of the fuel injection valvebefore the second mold member is molded thereto.

DESCRIPTION OF THE PREFERRED EMBODIMENT(S)

Embodiments of the fuel injection device for a direct injection engineof a motor vehicle are described in the following with reference to theappended drawings.

First Embodiment

FIG. 1 is a sectional view of an automotive internal combustion engineincluding a fuel injection device 30 given as a first embodiment of thepresent invention. As shown in FIG. 1, the automotive engine 1 includesa cylinder block 2 and a cylinder head 3 attached to the upper end ofthe cylinder block 2. The cylinder block 2 and the cylinder head 3 aremade of electro-conductive metallic material, and are electricallygrounded. The cylinder block 2 defines a plurality of cylinders 4, and apiston 5 is received in each cylinder 4 so as to be slidable in theaxial direction. A part of the cylinder head 3 opposing each cylinder 4is formed with a semi-spherical combustion chamber recess 6 whichdefines a combustion chamber 7 in cooperation with the upper face of thepiston 5.

A pair of intake ports 11 open out on one side of the combustion chamberrecess 6. Each intake port 11 extends from the combustion chamber recess6 to a side wall of the cylinder head 3 to open out therefrom. A pair ofexhaust ports 12 open out on the other side of the combustion chamberrecess 6. Each exhaust port 12 extends from the combustion chamberrecess 6 to an opposite side wall of the cylinder head 3 to open outtherefrom. The parts of the intake ports 11 and the exhaust ports 12opening out to the combustion chamber recess 6 are provided with intakevalves 13 and exhaust valves 14, respectively. A spark plug mountinghole 16 is passed vertically across the thickness of the cylinder head 3in a central part of the combustion chamber recess 6 surrounded by theintake ports 11 and the exhaust ports 12. A spark plug 17 is inserted inthe spark plug mounting hole 16, and fixed therein.

An end (inner end) of an injector hole 19 opens out at a side part ofthe combustion chamber recess 6 located between the two intake ports 11.The injector hole 19 extends linearly along an axial line thereof, andthe other (outer) end opens out from a side wall of the cylinder head 3.The outer end of the injector hole 19 is placed in a part of the sidewall closer to the cylinder block 2 than the intake ports 11. The outerend of the injector hole 19 is surrounded by a mounting seat 21 defininga plane perpendicular to the axial line of the injector hole 19. Theinjector hole 19 is provided with a circular cross section, and has adiameter that changes progressively in a middle part thereof from thewider outer end to the narrow inner end. Thus, the injector hole 19 ispassed across the thickness of the cylinder head 3, and communicates thecombustion chamber 7 with the exterior of the cylinder head 3.

A fuel injection device (injector) 30 is inserted in the injector hole19, and extends along a prescribed axial line A. The fuel injectiondevice 30 is provided with a free end (with respect to the axial line Athereof) which is exposed to the combustion chamber 7 and a base endextending out of the cylinder head 3 from the injector hole 19.

FIG. 2 is a perspective view of the fuel injection device (with a shieldcover thereof removed), FIG. 3 is a side view of the fuel injectiondevice, FIG. 4 is a perspective view of the fuel injection device asseen in the direction indicated by arrow IV in FIG. 3, and FIG. 5 is asectional view of the fuel injection device as mounted on the internalcombustion engine. As shown in FIGS. 2 to 5, the fuel injection device30 includes a valve body 33 having a fuel passage 32 defined therein, anozzle member 34 provided at the free end of the valve body 33, a valvemember 35 received in the fuel passage 32 so as to be moveable in theaxial direction, a solenoid (actuator) 37 for driving the valve member35 and a sensor 38 provided in a peripheral part of the free end thevalve body 33. A first resin portion 39 and a second resin portion(cover member) 40 are insert molded on the exterior of the valve body33.

The valve body 33 includes a first body 41, a second body 42 and a thirdbody 43. The first to third bodies 41 to 43 are made ofelectro-conductive, paramagnetic material. The first body 41 extendscoaxially to the axial line A of the fuel injection device 30, andincludes a small diameter portion 45, a tapered portion 46 and a largediameter portion 47 in that order from the free end to the base end. Thesmall diameter portion 45, the tapered portion 46 and the large diameterportion 47 are provided with circular cross sections, and are coaxial toone another. The large diameter portion 47 is provided with a largerdiameter than the small diameter portion 45, and diameter of the taperedportion 46 progressively increases from the free end to the base endthereof. The first body 41 is provided with a first hole 48 extendingthrough the length of the first body 41 in a coaxial relationship (tothe axial line A) from the free end to the base end thereof. The firsthole 48 is greater in diameter on the side of the large diameter portion47 than on the side of the small diameter portion 45.

The second body 42 includes a columnar shaft portion 51 extendingcoaxially with the axial line A of the fuel injection device 30 and adisk-shaped radial flange 52 extending radially outward from an outercircumferential surface of the shaft portion 51 at a certain distancefrom the free end of the shaft portion 51. The second body 42 iscoaxially connected to the first body 41 by fitting the free end of theshaft portion of the second body 42 into the large diameter portion 47of the first body 41. The inserting depth of the second body 42 into thefirst body 41 is determined by the abutting of the base end surface ofthe large diameter portion 47 of the first body 41 onto the flange 52 ofthe second body 42. A second hole 53 is passed through the length of theshaft portion 51 in a coaxial relationship to the axial line A. Byconnecting the first and second bodies 41 and 42 to each other, thefirst and second holes 48 and 53 communicate with each other, therebyjointly defining the fuel passage 32.

The third body 43 includes a cylindrical tubular portion 56 and an endwall 57 closing an end of the tubular portion 56. A circular insertionhole 58 is passed through the center of the end wall 57 in a coaxialrelationship. The inner circumferential surface of the tubular portion56 is provided with an enlarged portion dimensioned to receive theflange 52 of the second body 42 adjacent to the open end thereof. Thethird body 43 is combined with the first and second bodies 41 and 42 ina coaxial relationship by fitting the large diameter portion 47 of thefirst body 41 into the insertion hole 58 and placing the flange 52 ofthe second body 42 in the tubular portion 56 with the end wall 57located ahead of the tubular portion 56. The third body 43 is positionedwith respect to the first and second bodies 41 and 42 by the flange 52abutting an annular shoulder defined on the inner circumferentialsurface of the tubular portion 56. As a result, an annular solenoidchamber is defined by the tubular portion 56, the end wall 57 and theflange 52 around the outer circumferential surface of the large diameterportion 47 of the first body 41. The first, second and third bodies 41to 43 are fixedly joined to one another by welding performed inappropriate parts.

FIG. 6 is an enlarged sectional view of the free end of the fuelinjection device. As shown in FIG. 6, the nozzle member 34 includes atubular circumferential wall 61 and a bottom wall 62 closing an end ofthe circumferential wall 61 so as to define a cup-shape. Thecircumferential wall 61 is fitted into an open free end of the firsthole 48 with the bottom wall 62 located ahead of the circumferentialwall 61. The nozzle member 34 is fixedly attached to the first body 41by welding the free end of the circumferential wall 61 to the free endof the small diameter portion 45. The central part of the bottom wall 62bulges forward in a semi-spherical shape, and defines a valve seat 64 inthe recessed inner surface of this bulge. The central part of the bottomwall 62 is provided with a plurality of injection orifices 65 passedthrough the thickness thereof.

As shown in FIG. 5, the valve member 35 includes a rod 76 extendingthrough the first hole 48 along the axial line A and an enlargeddiameter portion 77 formed thereto. The enlarged diameter portion 77 hasan outer diameter which is greater than the inner diameter of the freeend of the second hole 53, and is configured to abut the front endsurface of the shaft portion 51. The free end of the rod 76 isconfigured to snugly seat on the valve seat 64 formed in the nozzlemember 34. The enlarged diameter portion 77 is provided with a pluralityof fuel holes 71 passed through the enlarged diameter portion 77 inparallel with the axial line A. Thus, the first hole 48 and the secondhole 53 communicate with each other via the fuel holes 71. The valvemember 35 is made of paramagnetic material.

A cylindrical spring seat 78 is press fitted into the second hole 53. Afirst spring 79 consisting of a compression coil spring is interposedbetween the spring seat 78 and the enlarged diameter portion 77 of thevalve member 35. The first spring 79 urges the valve member 35 towardthe free end so that the free end of the rod 76 is normally seated onthe valve seat 64 of the nozzle member 34, and the first hole 48 is shutoff from the injection orifices 65.

The solenoid chamber receives the annular solenoid (coil) 37 centeredaround the axial line A. The two ends of the coil wire of the solenoid37 are connected to a first and a second solenoid wire (drive signaltransmitting member) 83 and 84. The first and second solenoid wires 83and 84 are passed through through holes 89 formed in the flange 52, anddrawn out from the base end of the valve body 33. In an alternateembodiment, the two ends of the coil wire of the solenoid 37 are drawnout of the valve body 33, and are used as the first and second solenoidwires 83 and 84. The first and second solenoid wires 83 and 84 areintegrally bundled together over a most length thereof. In an alternateembodiment, the first and second solenoid wires 83 and 84 extend in amutually spaced apart, parallel relationship.

An annular O ring groove 85 is formed circumferentially around the baseend of the shaft portion 51. The O ring groove 85 receives an elastic Oring 86 therein. The open end of the second hole 53 in the base end partthereof is fitted with a filter 87 to remove foreign matters from thefuel.

The sensor 38 detects a state of the combustion chamber 7, and mayconsist of a per se known sensor such as a pressure sensor for detectinga pressure in the combustion chamber 7, a temperature sensor fordetecting a temperature in the combustion chamber 7 and an oxygen sensorfor detecting an oxygen concentration in the combustion chamber 7. Inthe first embodiment, the sensor 38 consists of a pressure sensorconsisting of a cylindrical piezo-electric device. The sensor 38 ismounted on the outer periphery of the free end of the small diameterportion 45 by receiving the free end of the small diameter portion 45 inthe central bore of the sensor 38. The sensor 38 is fixedly secured tothe small diameter portion 45 by welding such that the sensor 38 issupported by the free end of the valve body 33. As shown in FIG. 6, thebase end of the outer periphery of the sensor 38 is reduced in diameterin a step-wise fashion so as to define a connecting portion 88.

An end of a first sensor wire 91 (sensor signal transmitting member) fortransmitting an electric signal from the sensor 38 is connected to theconnecting portion 88 by soldering or the like. In the first embodiment,the first sensor wire 91 consists of a per se known flexible printedcircuit board (FPC) including electroconductive foil covered byinsulating film. In an alternate embodiment, the first sensor wire 91consists of a per se known cable including an electro-conductive membercovered by an insulating layer. As will be described hereinafter, thefirst sensor wire 91 extends to the base end along the exterior of thevalve body 33.

A seal device 92 is mounted on a part of the free end of the peripheryof the small diameter portion 45 on the base end side of the sensor 38.The seal device 92 includes a cylindrical collar member 93 receiving thesmall diameter portion 45 therein. The outer circumferential surface ofthe collar member 93 is provided with a pair of annular seal grooves 94extending circumferentially around the collar member 93. An annular gasseal member (tip seal) 95 is received in each seal groove 94. The freeend of the inner circumference of the collar member 93 is formed with areceiving portion 96 consisting of a step-wise enlarged diameterportion. The receiving portion 96 receives the connecting portion 88 ofthe sensor 38, and covers the exterior of the connecting portion 88. Thesensor 38 is welded to the collar member 93 at appropriate points. Thecollar member 93 fitted with the sensor 38 is press fitted into thesmall diameter portion 45, and is welded thereto at appropriate parts.

An engagement groove 97 is formed circumferentially around in a part ofthe outer circumference of the collar member 93 closer to the base endthan the two seal grooves 94. When press fitting the collar member 93fitted with the sensor 38 onto the small diameter portion 45, a tool(jig) is engaged by the engagement groove 97, and forced toward the baseend side of the small diameter portion 45, causing the collar member 93to be press fitted onto the small diameter portion 45. Because theengagement groove 97 is located on the side of the collar member 93remote from the sensor 38, the load applied by the tool is preventedfrom being transmitted to the sensor 38 so that the deformation andother influences on the sensor 38 can be minimized. Once the fuelinjection device 30 is placed in the injector hole 19, because theengagement groove 97 is located closer to the base end than the two gasseal members 95, the engagement groove 97 is not exposed to the gas fromthe combustion chamber including both the combusted gas and theuncombusted gas so that carbon and other foreign matters are preventedfrom being deposited in the engagement groove 97.

FIG. 7 is a perspective view of the fuel injection device (with theshield cover, the second resin portion and the stay member removed). Asshown in FIGS. 5 to 7, a first receiving groove 98 extending in theaxial direction over the small diameter portion 45, the tapered portion46 and the large diameter portion 47 is formed on the outer surface offirst body 41. The part of the first receiving groove 98 in the part ofthe small diameter portion 45 opposing the collar member 93 is providedwith a greater depth than other parts. The part of the first receivinggroove 98 having the greater depth extends from the part of the free endcorresponding to the receiving portion 96 beyond the part of the baseend corresponding to the collar member 93.

The free end of the tubular portion 56 is provided with a taperedsurface 99 extending over the entire circumferential surface anddefining a progressively smaller diameter toward the free end thereof.The part of the free end of the tubular portion 56 coinciding with thebase end of the first receiving groove 98 is formed with a recess 101which extends from the base end to the free end via the tapered surface99. The recess 101 is provided with a width (in the circumferentialdirection) broader than that of the first receiving groove 98.

A second receiving groove 103 is formed in a circumferentially centralpart of the recess 101 so as to correspond to the base end of the firstreceiving groove 98. The second receiving groove 103 extends from thefree end of the recess 101 to an axially intermediate part of thetubular portion 56 beyond the upper edge of the recess 101. A pair offirst engagement grooves 105 are formed on either side of the firstreceiving groove 98, and extend in parallel with the first receivinggroove 98. The free end of each first engagement groove 105 is locatedin the recess 101, and the base end of each first engagement groove 105extends to an axially intermediate point of the tubular portion 56. Anannular second engagement groove 106 is formed circumferentially aroundthe tubular portion 56 at a small distance from the base ends of thesecond receiving groove 103 and the first engagement grooves 105.

The first sensor wire 91 extends from the connecting portion 88 of thesensor 38 to the base end of the seal device 92 (collar member 93) alongthe first receiving groove 98, and further extends to the base end ofthe first receiving groove 98 or the base end of the small diameterportion 45 along the first receiving groove 98. Then, the first sensorwire 91 comes out from the first receiving groove 98, and extendstowards the base end along the outer surface of the tapered portion 46and the large diameter portion 47. Thereafter, the first sensor wire 91leaves the outer surface of the large diameter portion 47, and extendsinside the second receiving groove 103 until the first sensor wire 91reaches the base end of the second receiving groove 103. Thereafter, thefirst sensor wire 91 extends radially outward from the second receivinggroove 103, and terminates at the base end thereof spaced from the outersurface of the tubular portion 56.

FIG. 8 is a perspective view of the wiring arrangement for the first andsecond sensor wires. As shown in FIGS. 5 and 8, the base end of thefirst sensor wire 91 is supported by a stay member 108 at a prescribeddistance from the valve body 33. The stay member 108 consists of a platemember having a slit 109 in a middle part thereof and a projection 111at a bottom end thereof. The base end of the first sensor wire 91 ispassed into the slit 109, and the stay member 108 is bonded to the outersurface of the tubular portion 56. The stay member 108 can be axiallypositioned relative to the tubular portion 56 by the projection 111projecting into and being engaged by the second engagement groove 106.The base end of the first sensor wire 91 projects out of the slit 109 ofthe stay member 108, and is supported in this condition.

The first sensor wire 91 is stamp formed in a prescribed shapeconforming to the profile of the valve body 33, the first receivinggroove 98 and the second receiving groove 103 such that the first sensorwire 91 extends along the outer contour of the valve body 33. FIG. 9 isa sectional view showing the wiring arrangement for the first sensorwire 91, (A) showing the wiring arrangement on the exterior of the largediameter portion and (B) showing the wiring arrangement in the firstreceiving groove of the small diameter portion. As shown in FIGS. 9(A)and 9(B), except for the base end of the first sensor wire 91 thatprojects from the stay member 108, the first sensor wire 91 is coveredby an epoxy or other bonding agent 100, and thereby bonded to thesurface of the valve body 33. As shown in FIG. 9(A), in parts where thefirst receiving groove 98 and the second receiving groove 103 areabsent, the first sensor wire 91 is covered by the bonding agent 100,and thereby bonded to the surface of the large diameter portion 47, forinstance. As shown in FIG. 9(B), in parts where the first receivinggroove 98 (the second receiving groove 103) is present, the first sensorwire 91 is buried in and covered by the bonding agent 100 that fills thefirst receiving groove 98. The bonding agent 100 is also applied suchthat the gap between the base end of the collar member 93 and the smalldiameter portion 45 is sealed.

As shown in FIGS. 2, 5 and 7, the first resin portion 39 is molded onthe outer surface of the shaft portion 51. The first resin portion 39includes a cylindrical base portion 114 which covers the part of theshaft portion 51 ranging from the flange 52 to the base end thereof. Thefree end side of the base portion 114 of the first resin portion 39 isincreased in diameter to fill the annular space defined by the tubularportion 56, the flange 52 and the shaft portion 51. The part of the baseend of the outer circumference of the shaft portion 51 located moreforwardly than the O ring groove 85 is formed with an annular thirdengagement groove 116. The part of the inner circumference of thetubular portion 56 located more rearwardly than (on the open end sideof) the flange 52 is formed with an annular fourth engagement groove118. The base portion 114 of the first resin portion 39 is pushed intothe third and fourth engagement grooves 116 and 118, and engaged therebyso that the first resin portion 39 is fixedly secured to the valve body33 against an axial movement thereof.

The first resin portion 39 includes a connector portion 120 projectingsideways from the base portion 114. The connector portion 120 includes awall portion 121 extending radially along a plane perpendicular to theaxial line, and a tubular engagement portion 122 extending axially fromthe free end of the wall portion 121 to the side of the base end. Asshown in FIG. 4, the center of the wall portion 121 and the engagementportion 122 is offset sideways with respect to the radial line Bextending parallel to the projecting direction of the wall portion 121.In other words, the connector portion 120 is offset from the axial lineA. The engagement portion 122 is internally provided with a sensorconnecting terminal (first connecting terminal) 124, a first and asecond solenoid connecting terminal (second connecting terminals) 125and 126. The first solenoid connecting terminal 125 is placed in thecenter of the engagement portion 122, and the second solenoid connectingterminal 126 is located on the other side of the radial line B withrespect to the first solenoid connecting terminal 125. The sensorconnecting terminal 124 is located on the other side of the firstsolenoid connecting terminal 125 with respect to the second solenoidconnecting terminal 126. It is preferred that the sensor connectingterminal 124 is placed on the other side of the first solenoidconnecting terminal 125 with respect to the second solenoid connectingterminal 126 at some distance away from them. FIG. 11 is a perspectiveview similar to FIG. 4 showing a fuel injection device given as amodification of the first embodiment. As shown in FIG. 11, the sensorconnecting terminal 124 is desired to be spaced away from the first andsecond solenoid connecting terminals 125 and 126 as much as possible.The distance between the sensor connecting terminal 124 and the firstsolenoid connecting terminal 125 is greater than the distance betweenthe first solenoid connecting terminal 125 and the second solenoidconnecting terminal 126.

The first solenoid wire (drive signal transmitting member) 83 isconnected to the first solenoid connecting terminal 125, and the secondsolenoid wire (drive signal transmitting member) 84 is connected to thesecond solenoid connecting terminal 126. The first and second solenoidwires 83 and 84 are passed into the base portion 114 of the first resinportion 39 via the through holes 89 of the flange 52, and then into thewall portion 121 via the base portion 114. The first and second solenoidwires 83 and 84 extend in the radial direction in the wall portion 121,and enter the engagement portion 122. The first and second solenoidwires 83 and 84 are split from each other in the engagement portion 122,and are connected to the first and second solenoid connecting terminals125 and 126, respectively.

An end of the second sensor wire 128 is connected to the sensorconnecting terminal 124. The second sensor wire 128 is passed throughthe engagement portion 122 and the wall portion 121, and extends out ofa free end surface 129 of the wall portion 121 facing the free end side.Preferably, the second sensor wire 128 is spaced from the first andsecond solenoid wires 83 and 84 in the engagement portion 122 and thewall portion 121. The other end of the second sensor wire 128 projectingfrom the free end surface 129 is connected to a clip 131 consisting ofan electro-conductive metallic piece bent in a hair-pin shape bysoldering or any other known method. The base end of the first sensorwire 91 is engaged by the clip 131, and is electrically connectedthereto by soldering or any other known method.

FIG. 10 is a perspective view of the fuel injection device (with theshield cover removed, and with the first and second resin portionsshowing through). As shown in FIGS. 2, 5 and 10, the second sensor wire128 is surrounded by a shield member 133 that shields electro-magneticnoises. The shield member 133 consists of an electro-conductive metallicplate piece including a grounding portion 134 at an end thereof wrappedaround the shaft portion 51 and electrically connected thereto. Theshield member 133 further includes a trunk portion 135 that extendslinearly from the grounding portion 134 into the connector portion 120toward the projecting end thereof. The trunk portion 135 extends withinthe base portion 114 into the wall portion 121 along the first andsecond solenoid wires 83 and 84, and projects out of the projecting endof the wall portion 121 after passing through the gap by which thesecond sensor wire 128 is separated from the first and second solenoidwires 83 and 84 in the wall portion 121. The trunk portion 135 isprovided with a certain width in the axial direction so as to divide thewall portion 121 into two parts.

The free end of the trunk portion 135 projecting from the projecting endof the wall portion 121 is provided with an annular portion 136 which isbent so as to extend along the outer surface of the wall portion 121 andsurround the second sensor wire 128. The part of the trunk portion 135located in the wall portion 121 is bifurcated into a first branchportion 138 and a second branch portion 139. As shown in FIG. 4, thefirst branch portion 138 consisting of a plate member extends from theprojecting end of the trunk portion 135 into the engagement portion 122,and projects out of the gap between the first solenoid connectingterminal 125 and the sensor connecting terminal 124. As shown in FIG.10, the first branch portion 138 extends between the first solenoid wire83 and the second sensor wire 128. The second branch portion 139 alsoconsisting of a plate member extends from the base end portion of thetrunk portion 135 located in the wall portion 121 inside the free endsurface 129 in parallel with the free end surface 129. The second branchportion 139 is positioned so as to cover the base ends of the first andsecond solenoid wires 83 and 84.

The shield member 133, the first and second solenoid wires 83 and 84,the second sensor wire 128, the first and second solenoid connectingterminals 125 and 126 and the sensor connecting terminal 124 are atleast partly buried in the first resin portion 39 by insert molding.

As shown in FIGS. 2 and 5, the second resin portion 40 is molded on theexterior of the first body 41, the second body 42 and the first resinportion 39. The second resin portion 40 includes a first part 143covering the first body 41 and a second part 144 covering the secondbody 42 and a side of the base portion 114 of the first resin portion39.

The first part 143 is provided with a tubular shape so as to cover thepart of the small diameter portion 45 of the first body 41 on the baseend side of the collar member 93, the tapered portion 46, the largediameter portion 47 and the interface between the large diameter portion47 and the end wall 57 of the second body 42. The first part 143 coversthe first receiving groove 98 having the first sensor wire 91 placedtherein. As shown in FIG. 6, the end surface of the base end of thecollar member 93 contacting the first part 143 is formed with a fifthengagement groove 146 consisting of an annular groove extendingcircumferentially. The free end of the first part 143 is in contact withthe base end surface of the collar member 93, and extends into the fifthengagement groove 146 to be engaged thereby. As shown in FIGS. 2 and 5,the base end of the first part 143 engages the outer surface of the endwall 57 of the second body 42, and defines a tapering outercircumferential surface smoothly connected to the tapered surface 99.

The second part 144 extends in the axial direction (defined by the axialline A) so as to cover the second receiving groove 103 and the firstengagement grooves 105 as shown in FIG. 7. The free end of the secondpart 144 extends so as to cover the recess 101 toward the free end, andsmoothly continues with the first part 143. The base end of the secondpart 144 extends so as to contact a side portion of the first resinportion 39 opposing the shaft portion 51 and the free end surface of thewall portion 121, and covers the base end of the first sensor wire 91,the stay member 108, the clip 131 and the second sensor wire 128 thatprotrudes from the wall portion 121.

As shown in FIG. 7, the free end surface 129 of the wall portion 121 isformed with an engagement projection 148 projecting forward. Theengagement projection 148 is provided with a progressively increasingwidth toward the free end. In particular, the engagement projection 148of the first embodiment is provided with a rectangular cross sectionwith a progressively increasing area toward the free end. The width ofthe engagement projection 148 may either increase continually orincrease in a stepwise manner toward the free end. The second sensorwire 128 projects from the free end surface of the engagement projection148. The second part 144 of the second resin portion 40 is molded ontothe engagement projection 148 so as to wrap around the engagementprojection 148. As shown in FIG. 2, the second part 144 extends in thesecond engagement groove 106 along the length thereof, thereby definingan annular ring portion 149. By being engaged by the second engagementgroove 106, the ring portion 149 effectively prevents the second part144 from being dislodged from the second body 42.

As shown in FIG. 3, the wall portion 121 of the first resin portion 39and the second part 144 of the second resin portion 40 are covered by anelectro-conductive shield cover 150 which is attached to the annularportion 136 of the shield member 133 by welding. Thereby, the shieldcover 150 is electrically connected to the shield member 133.

The fuel injection device 30 having the structure discussed above ismounted on the engine such that the first body 41 is located in theinjector hole 19 and the third body 43 is located outside the injectorhole 19 as shown in FIGS. 1 and 5. An annular tolerance ring 152 isplaced on the mounting seat 21 provided on the outer end of the injectorhole 19 in a coaxial relationship to the injector hole 19. The tolerancering 152 is provided with an electro-conductivity, and is provided witha tapered surface on the inner circumference thereof in conformity withthe tapered surface 99 of the third body 43. Thereby, the valve body 33is electrically connected to the cylinder head 3 via the tolerance ring152, and is thereby grounded.

The free end of the first body 41 provided with the nozzle member 34 andthe sensor 38 is exposed in the combustion chamber 7. The seal device 92seals the interface between the injector hole 19 and the valve body 33by causing each gas seal member 95 to be in contact with the innercircumferential surface of the injector hole 19. As shown in FIG. 1, thebase end of the shaft portion 51 forming the base end part of the valvebody 33 is fitted into and connected to a connecting tube 161 providedin a delivery pipe 160 for supplying fuel to the fuel injection device30. The O ring 86 seals the interface between the shaft portion 51 andthe connecting tube 161 as discussed earlier. Thereby, the fuel drawnfrom the delivery pipe 160 may be supplied to the fuel passage 32consisting of the first hole 48 and the second hole 53 via theconnecting tube 161.

A connector (not shown in the drawings) of a wire harness extending froman ECU for controlling the fuel injection device 30 is connected to theconnector portion 120. Thereby, the sensor connecting terminal 124 andthe first and second solenoid connecting terminals 125 and 126 areconnected to the ECU via the wire harness so that the sensor signal fromthe sensor 38 is transmitted to the ECU, and the drive signal istransmitted from the ECU to the first and second solenoid wires 83 and84.

When the drive signal (voltage) is supplied to the solenoid 37 via thefirst and second solenoid wires 83 and 84, a correspondingelectromagentic field is generated by the solenoid 37. The magneticfield is conducted by a magnetic circuit formed by the free end of theshaft portion 51 of the second body 42, the enlarged diameter portion 77of the valve member 35, the tubular portion 56 and the end wall 57 ofthe third body 43, and the base end of the first body 41. The shaftportion 51 of the second body 42 serves as a yoke (fixed iron core), andthe enlarged diameter portion 77 serves as an armature (moveable ironcore) such that the enlarged diameter portion 77 is attracted to theshaft portion 51 against the biasing force of the first spring 79.Thereby, the free end of the rod 76 of the valve member 35 is displacedfrom the valve seat 64 of the nozzle member 34, causing the fuel to beinjected from the injection orifices 65 into the combustion chamber 7.When the supply of the drive signal to the solenoid 37 is stopped, theattractive force between the enlarged diameter portion 77 and the shaftportion 51 is lost so that the valve member 35 is caused to be movedtoward the free end thereof under the biasing force of the first spring79, and the free end of the rod 76 closes the injection orifices 65 byseating on the valve seat 64 of the nozzle member 34. As a result, theinjection of fuel is terminated.

The advantages of the fuel injection device 30 having the structurediscussed above are discussed in the following. As the first and secondsolenoid connecting terminals 125 and 126, and the sensor connectingterminal 124 of the fuel injection device 30 are provided in the sameconnector portion 120, the configuration of the fuel injection device 30can be simplified, and the connection to an external circuit can besimplified.

Because the first and second sensor wires 91 and 128 that connect thesensor 38 supported by the free end of the valve body 33 to the sensorconnecting terminal 124 are placed on the exterior of the valve body 33,the internal structure of the valve body 33 is not required to bechanged to accommodate the first and second sensor wires 91 and 128therein. Therefore, the fuel injection device 30 fitted with a sensor 38and the fuel injection device 30 not fitted with a sensor 38 can use asame valve body 33.

When the first and second sensor wires 91 and 128 are made of flexibleprinted circuit boards, and are thin enough to be placed along the outercontour of the valve body 33, the overall size of the fuel injectiondevice 30 is not required to be increased owning to the presence of thefirst and second sensor wires 91 and 128. Because the first and secondsensor wires 91 and 128 are covered by the bonding agent 100, thesewires are fixed in position. Therefore, even when the fuel injectiondevice 30 is subjected to vibrations owing to the repeated movement ofthe valve member 35, the first and second sensor wires 91 and 128 areprevented from moving so that the signal transmitted by the first andsecond sensor wires 91 and 128 is not contaminated by noises.

Because the first sensor wire 91 is fixedly secured to the valve body 33by the bonding agent 100 and the stay member 108 before the second resinportion 40 is molded, the first sensor wire 91 is allowed to maintainthe prescribed position when subjected to the pressure at the time ofinjection molding the second resin portion 40. Therefore, the firstsensor wire 91 can be kept at the prescribed position in the secondresin portion 40.

By being covered by the first and second resin portions 39 and 40, thefirst and second sensor wires 91 and 128 are prevented from contact withrainwater and other moisture. Because the first sensor wire 91, and theconnecting point between the first sensor wire 91 and the second sensorwire 128 are covered not only by the second resin portion 40 but also bythe bonding agent 100, the contact with moisture can be prevented evenmore effectively. The interface between the first resin portion 39 andthe second body 42 and the interface between the first resin portion 39and the third body 43 are protected from the intrusion of moisturebecause the first resin portion 39 is filled into the third engagementgroove 116 and the fourth engagement groove 118 so as to form aninterlocking engagement. Likewise, the interface between the secondresin portion 40 and the first body 41 and the interface between thesecond resin portion 40 and the third body 43 are protected from theintrusion of moisture because the second resin portion 40 is filled intothe first engagement grooves 105, the second engagement groove 106 andthe fifth engagement groove 146 so as to form an interlockingengagement. Also, because the second resin portion 40 is wrapped aroundthe engagement projection 148 of the first resin portion 39, andinterlocking features may be provided in the interface between the firstresin portion 39 and the second resin portion 40, the intrusion ofmoisture into this interface is effectively prevented.

The shield member 133 functions as an electromagnetic shield forcontaining the electromagnetic field generated by the drive signaltransmitted through the first and second solenoid wires 83 and 84 sothat the sensor signal transmitted by the first and second sensor wires91 and 128 and the sensor connecting terminal 124 is protected fromnoises. As the shield member 133 is grounded by being connected to thecylinder head 3 via the valve body 33 and the tolerance ring 152 whichare both electroconductive, the grounding structure can be simplified.The first branch portion 138 of the shield member 133 provides a shieldbetween the sensor connecting terminal 124 and the first solenoidconnecting terminal 125 in the engagement portion 122. The second branchportion 139 shields the free end of the first and second solenoid wires83 and 84, and prevents the drive signal transmitted by the first andsecond solenoid wires 83 and 84 from interfering primarily with thesensor signal transmitted by the first sensor wire 91.

The shield cover 150 functions as an electromagnetic shield forpreventing the electromagnetic field generated by the drive signaltransmitted by the first and second solenoid wires 83 and 84 of otherfuel injection devices 30 that are provided in conjunction with othercombustion chambers 7 from interfering with the sensor signaltransmitted by the first and second sensor wires 91 and 128 and thesensor connecting terminal 124. Because the annular portion 136 of theshield member 133 projects from the first resin portion 39 andelectrically connected to the shield cover 150, the grounding structurefor the shield cover 150 is simplified.

Because the sensor connecting terminal 124 is spaced apart from thefirst and second solenoid connecting terminals 125 and 126, theinfluences of the electromagnetic field generated by the first andsecond solenoid connecting terminals 125 and 126 on the sensorconnecting terminal 124 can be minimized. Similarly, because the secondsensor wire 128 connected to the sensor connecting terminal 124 isspaced apart from the first and second solenoid wires 83 and 84connected to the first and second solenoid connecting terminals 125 and126, respectively, the second sensor wire 128 is protected from theinfluences of the electromagnetic field generated by the first andsecond solenoid wires 83 and 84.

The first embodiment was directed to a fuel injection device using asolenoid as an actuator, but it is also possible to use a per se knownpiezoelectric device as an actuator. The cover member consisted of boththe second resin portion 40 and the bonding agent 100 in the firstembodiment, but only one of them may be used as the cover member. Thesensor signal transmitting member included the first and second sensorwires that are connected to each other by the clip 131, but it is alsopossible to use a single continuous wire as the sensor signaltransmitting member.

Second Embodiment

A second embodiment of the fuel injection valve (device) according tothe present invention is described in the following with reference tothe appended drawings. FIG. 12 is a block diagram showing the fuelinjection device 500 including a fuel injection valve 501 given as thesecond embodiment of the present invention. The fuel injection device500 includes an ECU 590 serving as fuel injection control unit inaddition to the fuel injection valve 501.

The ECU 590 receives information obtained from various sensors such asthe engine rotational speed, the boost pressure, the intake air amount,the intake temperature, the cooling water temperature and the fuelpressure, and controls the fuel injection in an optimum fashionaccording to the state of the engine (internal combustion engine).

The ECU 590 includes an injection amount computing unit 591 forcomputing an optimum amount of fuel injection according to the receivedinformation, and an injection time computing unit 592 for computing aninjection time according to the computation performed by the injectionamount computing unit 591.

The information on the injection pulse width computed by the injectiontime computing unit 592 is forwarded to the drive circuit 595. The drivecircuit 595 produces a drive current corresponding to the injectionpulse width, and supplies the drive current to an electromagnetic coil508 placed around a moveable valve member 506 of the fuel injectionvalve 501. Thereby, the moveable valve member 506 is opened under themagnetic attractive force, and maintains the open state for a timeperiod corresponding to the injection pulse width before the moveablevalve member 506 is closed once again. In other words, the fuelinjection valve 501 is opened and closed by using the electromagneticforce of the electromagnetic coil 508.

In this embodiment, a pressure sensor 560 is provided on the free end ofthe fuel injection valve 501 to detect the pressure in the cylinder. Thesignal produced from the pressure sensor 560 is forwarded to the ECU 590via a signal processing unit 598. The signal processing unit 598performs an analog to digital conversion process on the signal obtainedfrom the pressure sensor 560.

Referring to FIGS. 13 and 14, the structure of the fuel injection valve501 is described in the following. FIG. 13 is a side view of the fuelinjection valve 501 shown partly in section, and FIG. 14 is an externalperspective view of the fuel injection valve. The fuel injection valve501 consists of a solenoid actuated fuel injection valve configured todirectly inject fuel into the cylinder of the gasoline engine. The fuelinjection valve 501 includes a housing (yoke) 509 and a nozzle member504 including a part which is press fitted into the housing 509. Thehousing 509 further includes an elongated hollow cylindrical core 520provided in a lower part thereof and internally defining a fuel passage.The housing 509 is internally provided with an electromagnetic coil 508which surrounds the core 520.

As shown in FIG. 13, the moveable valve member 506 is positioned in thenozzle member 504 in a coaxial relationship with the central axial line(central axial line X) of the fuel injection valve 501. When theenergizing current is supplied to the electromagnetic coil 508, theresulting magnetic attractive force causes the moveable valve member 506to move upwardly in the drawing along the central axial line X, therebyopening the fuel injection valve 501.

The part of the core 520 protruding from the housing 509 is formed witha connector mold member (resin mold member) 570 on an outer peripheralpart thereof by a per se known injection molding process. A part of theconnector mold member 570 extends obliquely upward from the housing 509as seen in the drawing, and a free end thereof is formed into aconnector portion 570 a.

The connector mold member 570 retains a pair of energization currentexternal terminals 525 and a sensor external terminal 515 in a mutuallyinsulated condition. As shown in FIG. 12, an end of each energizationcurrent external terminal 525 is formed as an energization currentconnecting terminal 525 b which is connected to a wire 596 for supplyingthe energization current to the electromagnetic coil 508, and positionedin the connector portion 570 a (See FIG. 17). An end of the sensorexternal terminal 515 is connected to a wire 597 for obtaining thedetection signal of the pressure sensor 560, and is positioned in theconnector portion 570 a (See FIG. 17).

As shown in FIG. 13, the pressure sensor 560 for detecting the pressurein the cylinder is fixedly attached to the free end of the nozzle member504. A signal wire 550 is connected to the pressure sensor 560. Thesignal wire 550 consists of a conductor wire which is covered by asheath member except for an electric connecting parts thereof, and isconnected to the pressure sensor 560 at an end thereof and to the sensorexternal terminal 515 at the other end thereof. The detection signalobtained by the pressure sensor 560 is supplied to the ECU 590 via thesignal wire 550, the sensor external terminal 515 and the wire 597. Thesignal wire 550 extends along the outer surface of the housing 509 andthe nozzle member 504 (See FIGS. 13 and 16). The signal wire 550 isfixedly attached to the outer surface of the housing 509 and the nozzlemember 504 by using a bonding agent or the like, and is covered by asecondary mold member 580 along with the housing 509 and the nozzlemember 504.

As shown FIGS. 13 and 14, a tip seal holder 530 retaining a tip seal 540is provided in a part of the housing 509 adjacent to the nozzle member504. Referring to FIG. 15, the tip seal holder 530 provided adjacent tothe nozzle member 504 is described in the following. FIG. 15( a) is aschematic sectional view showing the free end part of the nozzle member504, and FIG. 15( c) is a sectional view taken along line A-A of FIG.15( a).

The tip seal holder 530 consists of a cylindrical member coaxiallydisposed to the central axial line X of the fuel injection valve 501.The outer circumferential surface of the tip seal holder 530 is providedwith a groove 531 extending in the circumferential direction. As shownin FIG. 15( a), a tip seal 540 consisting of an annular seal member isfitted into the groove 531.

The tip seal holder 530 is press fitted into an end of the nozzle member504, and is laser welded thereto at prescribed positions. In theillustrated embodiment, the nozzle member 504 is enlarged in diameter ata part thereof spaced from the free end thereof by a prescribeddistance, thereby defining a stepped portion 549. The stepped portion549 engages an end of the tip seal holder 530. The stepped portion 549is provided for the positioning of the tip seal holder 530. Whenassembling the tip seal holder 530 to the nozzle member 504, the tipseal holder 530 is press fitted onto the nozzle member 504 until an endof the tip seal holder 530 is engaged by the stepped portion 549 so thatthe positioning of the tip seal holder 530 is simplified.

As shown in FIGS. 13 and 15, an injector hole 503 is formed in thecylinder head 502. When the nozzle member 504 of the fuel injectionvalve 501 is passed into the injector hole 503, the interface betweenthe inner circumferential surface of the injector hole 503 and the outercircumferential surface of the tip seal holder 530 is sealed by the tipseal 540.

As shown in FIG. 15, the dimension D of the gap 538 between the innercircumferential surface of the injector hole 503 and the outercircumferential surface of the tip seal holder 530 is determined to beabout 0.2 mm. By limiting the dimension D of the gap 538 to be no morethan the prescribed dimension, the melting of the tip seal 540 owing tothe direct contact with the high temperature combustion gas can beavoided.

An insertion groove 532 is formed in the inner circumferential surfaceof the tip seal holder 530 along the central axial line X. The signalwire 550 of the pressure sensor 560 is received in the space defined bythe insertion groove 532 and the outer circumferential surface of thenozzle member 504.

The signal wire 550 extends from the pressure sensor 560 to a projectingpart 570 c of the connector mold member 570 via the insertion groove 532and the outer surfaces of the nozzle member 504 and the housing 509 asshown in FIG. 13. The signal wire 550 extends into a sloped portion 570b of the projecting part 570 c which faces the side of the pressuresensor 560, and is connected to a projecting part 515 a of the sensorexternal terminal 515 projecting toward the pressure sensor 560.

FIGS. 16, 17 and 18 are an external perspective view, a partly brokenaway perspective view and a partly in section side view of the fuelinjection valve before the secondary mold member 580 is molded thereto,respectively. As shown in FIG. 18, the energization current externalterminals 525 and the sensor external terminal 515 are fixedly attachedto the connector mold member 570 or the primary mold member.

As shown in FIG. 17, the outer ends of the energization current externalterminals 525 and the sensor external terminal 515 are exposed from theconnector portion 570 a of the connector mold member 570 as theenergization current connecting terminals 525 b and the sensorconnecting terminal 515 b, respectively. As shown in the drawings,because the energization current connecting terminals 525 b and thesensor connecting terminal 515 b are arranged in the same connectorportion 570 a, the electric connection between the electromagnetic coil508 and the corresponding wire 596 (See FIG. 12) and the electricconnection between the pressure sensor and the corresponding wire 597(See FIG. 12) are simplified.

As shown in FIGS. 17 and 18, the sensor external terminal 515 extendsfrom the sensor connecting terminal 515 b along the projecting part 570c of the connector mold member 570, and is bent at a point near thehousing 509 toward the pressure sensor 560 before further extending inparallel with the central axial line X. The other end of the sensorexternal terminal 515 remote from the sensor connecting terminal 515 bis formed as a projecting part 515 a which projects from a part of thesloped portion 570 b of the projecting part 540 c of the connector moldmember 570 facing the pressure sensor 560 toward the side of thepressure sensor as shown in FIGS. 16 and 18.

Referring to FIGS. 19 and 20, the connection between the signal wire 550and the sensor external terminal 515 fixed to the connector mold member570 is described in the following. FIGS. 19( a) and 19(b) are viewsshowing the processes of positioning and connecting the signal wire 550and the projecting part 515 a to each other, respectively. FIG. 20( a)is a view showing the process of bonding the signal wire 550 to theprojecting part 515 a, and FIG. 20( b) is a view showing the process ofsecondary molding. In FIGS. 19 and 20, the connecting portion betweenthe signal wire 550 and the projecting part 515 a is shown in anenlarged scale.

As shown in FIG. 19( a), before connecting the signal wire 550 and theprojecting part 515 a to each other, the signal wire 550 and theprojecting part 515 a are positioned to each other. As shown in FIG. 19(a), the conductor is exposed at the end part of the signal wire 550 bypeeling off the sheath 550 b thereof in advance. This exposed part 550 afrom which the sheath 550 b was removed is positioned so as to be incontact with the projecting part 515 a.

After this positioning process, as shown in FIG. 19( b), the exposedpart 550 a of the signal wire 550 is electrically connected to theprojecting part 515 a by depositing solder 551 thereonto. Uponcompletion of the soldering process, as shown in FIG. 20( a), a siliconebonding agent is applied to the entire circumference of the exposed part550 a of the signal wire 550 and the projecting part 515 a in theelectrically connected part, and is also applied to the sloped portion570 b of the connector mold member 570. Once the silicone bonding agentis cured, a layer 552 of the silicone bonding agent is formed around thecircumference of the exposed part 550 a of the signal wire 550 and theprojecting part 515 a. The layer 552 of the silicone bonding agent is inintimate contact with the sloped portion 570 b of the projecting part515 a.

In the secondary molding process, as shown in FIG. 20( b), the secondarymold member 580 is molded by a per se known injection molding process sothat the outer periphery of the housing 509 and the nozzle member 504,and the base part of the sloped portion 570 b of the projecting part 570c are covered by the secondary mold member 580. As a result, the signalwire 550 attached to the outer circumferential surface of the housing509 and the nozzle member 504, and the connecting portion between thesignal wire 550 and the projecting part 515 a are covered by thesecondary mold member 580.

In other words, as shown in FIG. 20( b), the exposed part 550 a of thesignal wire 550 and the projecting part 515 a are covered by the layer552 of the silicone bonding agent, and the layer 552 of the siliconebonding agent is in turn covered by the secondary mold member 580.Therefore, the exposed part 550 a of the signal wire 550 and theprojecting part 515 a are doubly covered so that a high level of waterproofing can be achieved.

Referring to FIG. 21, the improvement in the water proofing performanceowing to the covering of the exposed part 550 a of the signal wire 550and the projecting part 515 a with the layer 552 of the silicone bondingagent and the secondary mold member 580 is compared with that of aconventional example. FIG. 21( a) shows the example for comparison inwhich the secondary mold member 980 is formed without the presence ofthe layer 552 of the silicone bonding agent, and FIG. 21( b) shows thesecond embodiment of the present invention. In FIGS. 21( a) and 21(b),the movement of moisture in the interface 578 between the connector moldmember 570 and the secondary mold member 580 of the present invention iscompared with that that in the interface 978 between the connector moldmember 570 and the secondary mold member 980 by indicating the movementof moisture with arrows.

Moisture may intrude into an engine compartment in case of a heavyrainfall. As shown in FIG. 21( a), the moisture that deposited on thefuel injection valve 501 flows along the sloped portion 570 b of theconnector mold member 570, and reaches the interface 978 between theconnector mold member 570 and the secondary mold member 980. Owing tothe shrinking of the plastic material of the secondary mold member 980during the curing process in the die assembly, a small gap may becreated between the secondary mold member 980 and the connector moldmember 570. Therefore, the moisture may advance in the interface 978between the connector mold member 570 and the secondary mold member 980,and reach the projecting part 515 a.

On the other hand, according to the second embodiment of the presentinvention, as shown in FIG. 21( b), even when the moisture advanced inthe interface 578 between the connector mold member 570 and thesecondary mold member 580, any further advance is blocked by the layer552 of the silicone bonding agent. A small gap may be created betweenthe layer 552 of the silicone bonding agent and the secondary moldmember 580, because the exposed part 550 a or the projecting part 515 ais not in the path of the movement of the moisture, the moisture isprevented from being deposited on the exposed part 550 a or theprojecting part 515 a.

The second embodiment provides the following advantages.

-   (1) The fuel injection valve 501 includes the nozzle member 504, the    electromagnetic coil 508, the pressure sensor 560, the energization    current external terminal 525, the sensor external terminal 515, the    connector mold member 570 and the signal wire 550. The pressure    sensor 560 is attached to the front end of the nozzle member 504 to    detect the pressure in the cylinder. The energization current    external terminal 525 is connected to the wire 596 for supplying    electric current to the electromagnetic coil 508 at one end thereof,    and to the electromagnetic coil 508 at the other end thereof. The    sensor external terminal 515 is connected to the wire 597 for    obtaining the detection signal of the pressure sensor 560 at one end    thereof, and to the signal wire 550 at the other end thereof.

The signal wire 550 is connected to the pressure sensor 560 at one endthereof, and to the other end of the sensor external terminal 515 at theother end thereof. The other end of the sensor external terminal 515terminates as the projecting part 515 a projecting from the connectormold member 570, and the other end of the signal wire 550 terminates asthe exposed part 550 a free from the sheath 550 b. The projecting part515 a of the sensor external terminal 515 and the exposed part 550 a ofthe signal wire 550 are electrically connected to each other via thesolder 551.

The projecting part 515 a of the sensor external terminal 515 and theexposed part 550 a of the signal wire 550 are covered by the layer 552of silicone bonding agent, and the layer 552 of the silicone bondingagent is in turn covered by the secondary mold member 580.

As a result, even when moisture has intruded into the interface 578between the connector mold member 570 or the primary mold member and thesecondary mold member 570, the moisture is prevented from advancing bythe layer 552 of the silicone bonding agent. As a result, the waterproofing performance of the electric connection between the sensorexternal terminal 515 and the signal wire 550 can be enhanced.

-   (2) Because the energization current external terminal 525 and the    sensor external terminal 515 are retained by the same single    connector mold member 570, the electrical connection of the fuel    injection valve 501 with an external circuit is facilitated.-   (3) The fuel injection valve 501 includes the cylindrical tip seal    holder 530 mounted on the nozzle member 504 and the annular tip seal    540 mounted on the tip seal holder 530 so as to seal the interface    between the inner circumferential surface of the injector hole 503    and the outer circumferential surface of the tip seal holder 530.    Therefore, by adapting the tip seal holder 530 to the diameter of    the injector hole 503, the dimension D of the gap between the fuel    injection valve 501 and the injector hole 503 on the pressure sensor    side of the tip seal holder 530 can be maintained to be no more than    a prescribed value so that the tip seal 540 is prevented from    melting.

In other words, according to this embodiment, the tip seal holder 530may be formed so as to correspond to the diameter of the injector hole503, and the nozzle member 504 is not necessarily required to be adaptedto the diameter of the injector hole 503. Therefore, the nozzle member504 of the same configuration may be placed in various injector holes503 having different diameters, and this contributes to the improvementin the production efficiency.

The nozzle member 504 of the fuel injection valve 501 is formed with astepped portion 549 configured to engage an end of the tip seal holder530. By press fitting the tip seal holder 530 onto the nozzle member 504until an end of the tip seal holder abuts the stepped portion 549, thepositioning of the tip seal holder 530 can be accomplished in a simplemanner. Owing to the simplification of the positioning process, theproduction efficiency can be improved, and the manufacturing cost can bereduced.

-   (4) The nozzle member 504 of the fuel injection valve 501 is    provided with the stepped portion 549 for engaging an end of the tip    seal holder 530. When assembling the tip seal holder 530 to the    nozzle member 504, the tip seal holder 530 is press fitted onto the    nozzle member 504 until an end of the tip seal holder 530 is engaged    by the stepped portion 549 so that the positioning of the tip seal    holder 530 is simplified, and this also increases productivity and    reduces the cost.-   (5) An insertion groove 532 is formed in the inner circumferential    surface of the tip seal holder 530 along the central axial line X.    Therefore, the pressure sensor 560 mounted on the front end of the    nozzle member 504 can be electrically connected to the sensor    external terminal 515 without compromising the sealing performance.-   (6) The outer circumferential surface of the tip seal holder 530 is    formed with the circumferential groove 531 for receiving the tip    seal 540 so that the fitting of the tip seal 540 in the tip seal    holder 530 is simplified. Also, the groove 531 can effectively    retain the tip seal 540 in the prescribed position so that the    leakage of combustion gas from the cylinder can be avoided with a    high reliability.

Third Embodiment

A fuel injection valve 701 given as a third embodiment of the presentinvention is described in the following with reference to FIGS. 22 and23. FIG. 22 is a partly in section side view showing the fuel injectionvalve 701 of the third embodiment, and FIG. 23 is an externalperspective view showing the fuel injection valve 701 before thesecondary mold member 780 is molded thereto. In the followingdescription, the parts corresponding to those of the previousembodiments are denoted with like numerals without necessarily repeatingthe description of such parts. Thus, only the parts that differ fromthose of the previous embodiments are described in great detail in thefollowing description.

In the second embodiment, the projecting part 515 a projected from thesloped portion 570 b of the projecting part 570 c of the connector moldmember 570 facing the pressure sensor 560 in parallel with the centralaxial line X of the fuel injection valve 501 (See FIG. 13). In the thirdembodiment, a protrusion 771 projects from the sloped portion 770 b ofthe projecting part 770 c of the connector mold member 770 facing thepressure sensor 560 in parallel with the central axial line X of thefuel injection valve 701.

The protrusion 771 includes a planar side surface 771 a extending inparallel with the central axial line X and a top surface 771 b extendingperpendicularly to the central axial line X. In the third embodiment,the projecting part 515 a of the sensor external terminal 515 projectsfrom the top surface 771 b of the protrusion 771 toward the pressuresensor 560.

According to this third embodiment, the advantages similar to those ofthe second embodiment can be obtained. Furthermore, according to thethird embodiment, the path length for the moisture that may intrude intothe interface between the secondary mold member 780 and the connectormold member 770 (or the primary mold member) to reach the layer 552 ofthe silicone bonding agent can be increased. Therefore, even whenmoisture should intrude into the interface, the moisture will evaporatebefore reaching the layer 552 of silicone bonding agent. Therefore, thethird embodiment provides an even more enhanced water proofingperformance than the second embodiment.

The following modifications are also within the purview of the presentinvention, and one or a plurality of these modifications may be combinedwith any of the foregoing embodiments.

-   (1) The sensor provided on the front end of the fuel injection valve    501 consisted of a pressure sensor 560 in the foregoing embodiments,    but the present invention is not limited by such embodiments. For    instance, a thermocouple for detecting the temperature in the    cylinder may be mounted on the free end of the fuel injection valve    as such a sensor without departing from the spirit of the present    invention.-   (2) The protrusion 771 is caused to intrude into the interface    between the connector mold member 770 and the secondary mold member    780 for the purpose of increasing the path length which the moisture    must travel in order to reach the layer 552 of the silicone bonding    agent in the third embodiment, but the shape of the protrusion 771    is not limited to that given in the third embodiment. Even more    irregularly shaped protrusions may also be used for increasing the    path length of the moisture even further.-   (3) The insertion groove 532 was provided in the inner    circumferential surface of the tip seal holder 530 in the foregoing    embodiments, but the present invention is not limited by such    embodiments. Instead of providing the insertion groove 532 in the    inner circumferential surface of the tip seal holder 530, an    insertion groove may be formed in the outer circumferential surface    of the nozzle member 504 along the central axial line X to receive    the signal wire 550 connecting the pressure sensor 560 to the sensor    external terminal 515 therein.-   (4) The exposed part 550 a of the signal wire 550 was electrically    connected to the projecting part 515 a via the solder 551 in the    foregoing embodiments, but the present invention is not limited by    such embodiments. For instance, a low-temperature sinter bonding    material containing silver foil and small metallic particles may    also be used for connecting the exposed part 550 a of the signal    wire 550 to the projecting part 515 a.

Although the present invention has been described in terms of preferredembodiments thereof, it is obvious to a person skilled in the art thatvarious alterations and modifications are possible without departingfrom the scope of the present invention.

Glossary

-   1 internal combustion engine-   3 cylinder head (engine main body)-   7 combustion chamber-   19 injector hole-   30 fuel injection device-   32 fuel passage-   33 valve body-   34 nozzle member-   37 solenoid (actuator)-   38 sensor-   39 first resin portion-   40 second resin portion (covering material)-   41 first body-   42 second body-   43 third body-   45 small diameter portion-   46 tapered portion-   47 large diameter portion-   51 shaft portion-   56 tubular portion-   57 end wall-   65 injection orifice-   83 first solenoid wire (drive signal transmitting member)-   84 second solenoid wire (drive signal transmitting member)-   91 first sensor wire (sensor signal transmitting member)-   92 seal device-   93 collar member-   94 seal groove-   95 gas seal member-   97 engagement groove-   98 first receiving groove (receiving groove)-   99 tapered surface-   100 bonding agent (covering member)-   101 recess-   103 second receiving groove (receiving groove)-   105 first engagement groove-   106 second engagement groove-   108 stay member-   114 base portion-   120 connector portion-   121 wall portion-   122 engagement portion-   124 sensor connecting terminal (first connecting terminal)-   125 first solenoid connecting terminal (second connecting terminal)-   126 second solenoid connecting terminal (second connecting terminal)-   128 second sensor wire-   129 free end surface-   131 clip-   133 shield member-   134 grounding portion-   135 trunk portion-   136 annular portion-   138 first branch portion-   139 second branch portion-   143 first part-   144 second part-   146 fifth engagement groove-   148 engagement projection-   150 shield cover-   152 tolerance ring-   A axial line-   B radial line-   500 fuel injection device-   501 fuel injection valve-   502 cylinder head-   503 injector hole-   504 nozzle member-   506 moveable valve member-   508 electromagnetic coil-   509 housing-   515 sensor external terminal-   515 a projecting part-   515 b sensor connecting terminal-   520 core-   525 energization current external terminal-   525 b energization current connecting terminal-   530 tip seal holder-   531 groove-   532 insertion groove-   538 gap-   540 tip seal-   549 stepped portion-   550 signal wire-   550 a exposed part-   550 b sheath-   551 solder-   552 layer of a silicone bonding agent-   560 pressure sensor-   570 connector mold member-   570 a connector portion-   570 b sloped portion-   570 c projecting part-   578 interface-   580 secondary mold member-   585 interface-   590 ECU-   591 injection amount computing unit-   592 injection time computing unit-   595 drive circuit-   596, 597 wire-   598 signal processing unit-   701 fuel injection valve-   770 connector mold member-   770 b sloped portion-   770 c projecting part-   771 projection-   771 a planar side portion-   771 b top surface portion-   780 secondary mold member-   978 interface-   980 secondary mold member

1. A fuel injection device, comprising: a valve body having a free endexposed to a combustion chamber defined in an engine main body and abase end located outside of the engine main body; a sensor supported atthe free end of the valve body to detect a state of the combustionchamber; an actuator received in the valve body; a sensor signaltransmitting member extending from the sensor to the base end of thevalve body; a drive signal transmitting member extending from theactuator; and a first shield member interposed between the sensor signaltransmitting member and the drive signal transmitting member, the firstshield member having an electro-conductive property and being grounded.2. The fuel injection device according to claim 1, wherein the valvebody is provided with an electro-conductive property and grounded viathe engine main body, and the first shield member is supported by andelectrically connected to the valve body.
 3. The fuel injection deviceaccording to claim 2, further comprising: a first resin portion moldedto the base end of the valve body to define a connector portion; a firstconnecting terminal placed in the connector portion and connected to thesensor signal transmitting member; and a second connecting terminalplaced in the connector portion and connected to the drive signaltransmitting member, the first shield member being at least partlyburied in the first resin portion.
 4. The fuel injection deviceaccording to claim 3, wherein the first shield member includes a partinterposed between the first and second connecting terminals.
 5. Thefuel injection device according to claim 3, further comprising: a secondresin portion molded to the valve body and the first resin portion andcovering the sensor signal transmitting member; and a second shieldmember having an electro-conductive property and covering the secondresin portion, the second shield member being electrically connected toa part of the first shield member extending from the first resinportion.
 6. The fuel injection device according to claim 3, wherein thesecond connecting terminal comprises a pair of second connectingterminals which are placed on either side of a diametric line extendingperpendicular to an axial line of the valve body, and the firstconnecting terminal is positioned on a side of one of the secondconnecting terminals facing away from the other second connectingterminal.
 7. The fuel injection device according to claim 6, wherein adistance between the first connecting terminal and the adjoining secondconnecting terminal is greater than a distance between the two secondconnecting terminals.